The present invention generally relates to fabrication of electron devices such as semiconductor devices or magnetic devices and more particularly to the manufacturing method of a photomask used for fabricating electron devices as well as a fabrication process of an electron device by using such a photomask.
In the fabrication of electron devices such as semiconductor devices or magnetic devices, it is generally practiced to transfer a device pattern image held on a photomask in the form of an opaque pattern onto a substrate such as a silicon wafer by way of an exposure process.
Particularly, with recent electron devices of high-performance and versatile functions, there are imposed ever stringent demands of form fidelity and high dimensional precision in view of the miniaturization of device patterns.
Thus, manufacturing of a photomask has generally conducted conventionally by using a high-resolution electron beam exposure apparatus for exposing opaque patterns, and dry etching has been used in the etching process for patterning the opaque film such as a Cr film to form the desired opaque pattern, in view of the nature of the dry etching process of small pattern variation at the time of etching.
Generally, a photomask is classified to a positive photomask and negative photomask, the positive photomask being formed by using a positive resist while the negative photomask is formed by using a negative resist. The resist type is selected as minimum exposure time dependency but occasionally using a negative resist forms a photomask having critical dimensional patterns in use of gate layer.